Understanding the variation in the adult male zebra finch song and behaviour, during courtship, with distance of communication

Abstract

Communication in animals depends on factors that enhance or attenuate transmission of acoustic signals and which, in turn, are necessary for development of strategies for effective communication. One such prominent factor that affects signal transmission is the communication distance between the sender and the receiver. It has been shown that animals strategically change the intensity of their vocalisations to compensate for the losses incurred during signal transmission over long distances. However, the influence of this communication distance on acoustic features other than intensity has not been investigated. The song of the zebra finch birdsong model system provides us with an array of acoustic features which are distinct in different social contexts and hence, making these birds suitable candidates for examining the influence of communication distance on the acoustic properties of their song. In order to do this, we recorded and analysed the courtship song features at five different distances and found that, with increase in distance from the female zebra finch, the male bird song features become less rigorous. At longer distances, the courtship songs resemble the songs sung by these birds in isolation. On the other hand, when we tried to validate the variation in song amplitude with distance, we, surprisingly, found no change. Together, our findings suggest that communication distance is one of the crucial factors influencing acoustic properties essential for effective communication.